Why is the Shellac bubbling up and lifting off bottom of canoe?

[Brightraven]

Hello!

I have an Island Falls 16' Wilderness Guide that I was eager to take out on the water for the first time today, but I was surprised and disappointed to see a series of "bubbles" in the shellac that have lifted up off the bottom of the canoe. Last Autumn, I applied a layer of shellac to the bottom of the hull and it looked great. It performed just fine for a few times before it was stored in my garage throughout the winter. The "bubbles" feel too thin to be canvas, and can be easily pressed down (before they pop up again). Does anyone have any ideas why this has happened and what I can do to remedy the situation? I have included photos.

Many thanks,
Gregor

 

[MGC]

Gregor,
I have several canoes finished with shellac bottoms. It's a great way to finish off a working canoe. The little bit if maintenance they require is a small price to pay for such a versatile bottom finish.
Frankly, I am not seeing any "bubbles" in your shellac. Possibly it's the way that the images were captured? What I do see are what look like canvas puckers. They are of the sort that you might get if the canvas was not stretched enough. For them to appear long after the boat was finished is a bit odd, but you mention paddling it before winter storage. Somewhere in that process the canvas may have relaxed itself enough to pucker.
If it were me, I'd simply take it out for a paddle and see what happens. Those puckers may go away on their own.
Good luck!
Mike

 

[Brightraven]

Thanks for your reply, Mike. This “puckering” or whatever it is seems to be too thin to be canvas from my inexperienced point of view. I can easily push them down and they feel quite thin and flimsy. Wouldn’t the canvas have a thicker feel to it?
I got the boat used last summer and apparently it was very rarely used at all. It is about 20 years old and canvas has seemed ok, but the shellac was thinning out last year so that’s why I added a new coat.
How would I know if this is the canvas starting to pucker?
Many thanks

 

[MGC]

I had one pucker like that. It was literally months after I canvased it. It was filled, cured, painted and suddenly puckers appeared. It was a torpedo stemmed canoe that I probably did not get tight enough due to the odd shape. I also suspected that it was too early in the spring when I filled it. Who knows. I ended up removing the canvas and redoing it.
Your canoe was built by one of most renowned and premier builders. It seems so unlikely that anything amateurish (as in my case) was done during it's construction.
That said, if the canoe was rarely used and now suddenly is, it's possible that something has gone off the rails. I think it should be easy to tell if the canvas is puckered up. If you can push on it and there is some space between the filled canvas and the planking, it's puckered.
If the canoe has been so infrequently used you might have some gaps between the planking. In that case you might be able to see that the canvas is spaced away from the planking by looking from the inside of the canoe?
Whatever the case, it might not hurt to give Jerry a call and ask him what he knows about the boat. He might have used a thinner canvas on it to save weight.

 

[Brightraven]

Thanks for the response, Mike. I'll contact Jerry about it...